In mass processing of food product, food product is often heated by cooking or blanching the food product in a food processing apparatus having a tank holding a heat transfer medium into which the food product is immersed. After cooking or blanching of the food product occurs, the food product may be cooled or chilled by immersing the food product in a cool transfer medium so that the food product may be packaged, stored and/or shipped. In some known systems, a rotary drum blancher or a rotary screw blancher is used to first cook or blanch the food product, and the food product is discharged onto a belt or other type of conveyor and advanced to a rotary cooler to reduce the food product temperature to an acceptable temperature. In another known system, a single compact apparatus (e.g., a combination cooker-cooler) is used to heat and cool the food product in continuous flow.
In a rotary drum blancher, food product is introduced into an inlet end of an elongate drum, which is rotatably mounted in a generally cylindrical, open-top tank. The tank is fitted with a cover for minimizing heat loss and for enclosing the drum for safety reasons, and which can be opened for maintenance and cleaning. The drum includes an auger therein for advancing food product from the inlet end of the drum to an outlet end of the drum and through the heat transfer medium. The drum includes a structural frame with perforated skin panels that are typically bolted on or can be partially or fully removable from the drum.
In a rotary screw blancher, food product is introduced into an inlet end of a generally cylindrical, open-top tank. A rotatable auger is mounted within the tank for advancing food product from the inlet end to an outlet end of the tank and through a heat transfer medium. The tank is fitted with a cover for minimizing heat loss and for enclosing the auger for safety reasons, and which can be opened for maintenance and cleaning.
The rotary blancher is generally used to cook a variety of food products, including pasta, rice, vegetables, dry beans, pouched meat, pouched sauces, etc. Cleanliness is a concern in the food processing industry, and strict hygienic standards and inspections are observed throughout the industry for machinery that comes in contact with food for human consumption. Many facilities will process small batches of a variety of products in a single day or shift, which requires cleaning of the rotary blancher, and in particular the drum, between product runs. It is necessary for rotary blanchers to provide access for cleaning sprays to all joints and cavities within the drum where contaminant accumulation may occur. In some rotary drum blanchers, it is necessary to remove perforated skin panels from the drum frame or reposition access doors of the drum to perform the necessary cleaning. Such actions require high levels of labor and machine down time.
One solution is use of a rotary screw blancher, which is easier to clean because the rotary screw blancher lacks a drum and has higher food product capacity than similarly sized rotary drum blanchers because food product can run at deeper depths. However, the auger causes more damage to food product as compared to rotary drum blanchers, especially if food product is caught in clearance gaps between the auger and the tank.
Some prior art rotary screw blanchers include an inner screen with a very small clearance between the auger and the screen to reduce damage to product. The screen also allows water flow from one auger flight to the tank surrounding the screen, and thus to another flight. One example of such a prior art rotary screw blancher may be found in U.S. Pat. No. 7,735,415, hereby incorporated by reference. The rotary blancher described therein includes the ability to move the screen from a first position for using the blancher, to a second position for cleaning the blancher.
Another rotary screw blancher is described in US Patent Application Publication 20110072980, hereby incorporated by reference, and includes an auger with close clearance to a solid imperforate tank. A screen panel with side channels is provided to allow water flow between the auger flights. The screen panels are moveable (or removable) to allow cleaning behind the screens.
Prior art rotary screw blanchers have included several discharge mechanisms, including a ferris wheel style (shown in U.S. Pat. No. 7,735,415) and a plenum style (shown in application publication 20110072980 and in U.S. Pat. No. 8,006,613, hereby incorporated by reference).
One need of the prior art is the ability to transition from the auger portion of the blancher to the discharge portion, and to provide easy cleaning of the transition zone. If this distance is short, there is less likelihood of product falling outside the area intended to contain the product, but this puts several large plates of sheet metal close together, and this is difficult to clean. If the transition is extended, then cleaning of the large plates becomes easier, but there is a hidden surface on the underneath side of this transition that requires access doors to visually inspect, or mirrors or other devices are required. Cleaning of this area has been a concern for food processing companies that process Ready to Eat meals (RTE's) or companies with high sanitation requirements. A close transition is desirable to allow the product to move from the main tank to the discharge section of the tank.